Processes for producing semiconductors or liquid crystals involve a plasma treatment of silicon wafers in various steps such as CVD step, etching step, ashing step, etc. Particularly, for organic polymer materials used as seals, etc. in the apparatuses for producing semiconductors or liquid crystals, the plasma treatment is carried out under very severe conditions, so almost all of the organic polymer materials inevitably suffer from heavy deterioration during the exposure to the plasma atmosphere.
As to the seals used in the afore-mentioned apparatuses, inorganic compounds, etc. contained as a filler in the seal materials are generated as particles due to deterioration of organic polymer materials by plasma, thereby contaminating the wafer surfaces. Thus, it is necessary to prevent the seal materials exposed to the plasma atmosphere from generation of such inorganic compounds leading to product failure.
It is necessary that the fluorine-containing elastomer so far used as a seal material is further admixed with a reinforcing agent such as carbon black, silica, titanium oxide, etc. as a filler to improve normal state physical properties such as mechanical strength, compression set, etc. and furthermore in the case of polyol vulcanization or amine vulcanization it is necessary to add thereto an acid acceptor such as a metal compound of Mg, Pb, Ca, Al, Zn, or the like as a vulcanization promoter besides the vulcanizing agent. These inorganic fillers turn to be a source for generating the particles. On the other hand, the fluorine-containing elastomers made free from any inorganic filler as a source of generating the particles suffer not only from a failure of attaining the necessary normal state physical properties for the seal materials, but also from deterioration of the kneadability during the kneading.
Even if no such inorganic fillers are used, the deteriorated seal materials per se may turn to be a source for generating the particles, and thus even in the case of organic polymer materials per se for use in the seal materials, it is required reduction in the amount of generated particles, in other words, enhancement of plasma resistance.
It has been so far proposed in view of such backgrounds to reduce the amount of an inorganic filler to be used to suppress the particle generation and to use PTFE powder as a filler, etc. instead. The proposed filler indeed has a distinguished CF4 plasma resistance, but the O2 plasma resistance is not satisfactory, and thus has not yet satisfied the requirements imposed for use in the apparatuses for producing semiconductors or liquid crystals. Various plasma-resistant seal materials so far proposed for such use are as follows:    Patent Literature 1: JP-A-2000-119468    Patent Literature 2: JP-A-2002-173543    Patent Literature 3: JP-A-2004-131656
It has been still now required in view of a demand for further upsizing of silicon wafers and finer wiring patterns to develop seal materials not only capable of withstanding more severe plasma treatment conditions, but also having a distinguished plasma resistance, irrespective of plasma gas species. Furthermore, improvement of not only reduction in weight as a basic measure of plasma resistance, but also cracking resistance during the plasma irradiation as another basic measure of seal life has been newly required.